1. Field of the invention
This invention relates to a switch mechanism for an electronic timepiece which makes use of an electro-optical display element such as a liquid crystal, photodiode and the like capable of displaying date, time, week days and the like. The switch mechanism serves to effect an erasure, correction and the like of the display.
2. Description of the prior art
This display element used for this kind of electronic timepiece can be made small so that it is particularly applicable to a wristwatch whose size is small. In addition, the display element must be operated with the aid of a battery for a long time and must easily be discernible. Particularly, a liquid crystal display element consumes less electric power when compared with the other kind of display and is only several tens of microns in thickness and provides the advantage that it can be made small in size and easily discernible even in the bright light. The liquid crystal, however, has the disadvantage that it becomes less discernible in the dark, and that its life is rather short because deterioration of the liquid crystal.
In order to easily discern the display in the dark, a timepiece comprising a liquid crystal display element has heretofore been proposed which makes use of a light source for illuminating the liquid crystal display element and incorporated in the timepiece and a switch mechanism which, when operated energizes the light source so as to illuminate the display surface.
A display element composed of a photodiode can be clearly seen in the dark, but has the disadvantage that the electric power consumed is large so that the battery for use with the wrist watch can not be used for continuous display over a long time.
In order to avoid this disadvantage an electronic timepiece makes use of the photodiode display element and in which for the sake of economy of the electric power the display is normally erased or cancelled and a switch mechanism is operated only when the user wishes to know time. The user then operates the display element and hence displays the time.
Such prior-art switch mechanism, however, has the disadvantage that provision must be made of an exteriorly operated member for each switch independently of another exteriorly operated member serving as a display correction switch, and as a result, the exteriorly operated members for all of the switches become large in number. There is also the risk that the exteriorly operated members may be erroneously operated and, in addition, that the electronic timepiece may be of poor design.
Moreover, the prior-art electronic timepiece which can display not only the hour and minutes but also seconds, date, weekday and the like creates the need for a number of places to be corrected which makes the correction of each display complex; as a result, there is the risk that other displays will be erroneously effected. In order to prevent such erroneous operation due to the increase in number of the display elements, it has been proposed to provide a mark for indicating the correction display element at the periphery of the time display element for the purpose of indicating the display element being corrected. The use of such mark for the purpose of confirming the place to be corrected results in an addition of displays not required for the time display. As a result, the display part, switch part, electrical circuit and the like become highly complex, thereby making the electronic timepiece expensive.